In a current network, there are various network devices, such as routers, gateways, switches, firewalls, and various servers. The devices that implement various network functions generally include respective control modules, and the distributed control modules lead to an extremely complex network deployment.
To improve network deployment flexibility and manageability, a software-defined networking (Software Defined Network, SDN) concept is put forward in the industry. In SDN, a control plane device implements network control and management functions, and a forwarding plane device implements a forwarding function in a network. OpenFlow (OpenFlow) is a mainstream SDN network control protocol at present. In the OpenFlow, a control plane device controls behavior of a forwarding plane device by using a flow entry. The flow entry may indicate a data packet that needs to be processed and a corresponding operation.
QoS refers to a network capability to provide a service of a higher priority. Quality of service of a network can be improved by performing QoS control on a data packet. In a conventional network, because each network element itself is integrated with a control function, QoS control on a data packet is extremely easy to perform. However, for an SDN network, currently there is no mechanism to implement a QoS control function.